They would just "forget" about arresting him or purposefully started some kind of long procedural judicial consultation ("something, something, Diplomatic Immunity"), for long enough that Carney had time to properly lick Netanyahu's arse and the latter left Canada.

Following that there would be some theatrical political performances on the theme "we could never imagine this could happen" including some deeply emotional "lessons were learned" at the end for that oh so very special "we're really genuinelly sorry and this will never happens again (until it does)" juice.